Fable Walkthrough
The Basics : Will
As you gain experience, there are three basic types of attributes you can increase: Strength, Skill, and Will. Will controls everything to do with magic power. I highly suggest you build up your mana bar and then get the multi-lightning, heal others, and mana shield.

Magic Power
This controls how much actual mana you can have stored up at one time, the blue bar.

Lightning
This is the first spell you learn and it is REALLY useful especially when you learn how to attack multiple enemies with it. I highly recommend even if you're not a magic-user to beef this one up to use on high-up enemies.

level 1: automatic
level 2: 5,760 xp
level 3: 18,200 xp

Multi Arrow
Everyone learns archery of course, and while it might seem a pain to use all the time, it is perfect for sniping in certain conditions. If you learn multi arrow, then it causes your sniping to send multiple arrows. Quite helpful when you are sneaking up on someone. Note the multi-arrow spell causes four blue spheres to go around you, to indicate it's active.

level 1: 1,000 xp
level 2: 5,140 xp
level 3: 19,500 xp

Slow Time
This is very handy in any combat situation, to get you around and attacking the enemy before they can strike back.

level 4: 47,500 xp

Heal
VERY useful especially when you are on protection quests, since you can fix any wounds they may get.